The invention relates to a tool spindle for a device for fine machining optically active surfaces on workpieces, having a spindle housing and a tool holding portion which protrudes beyond the housing. The tool holding portion can be axially advanced towards the workpiece along a tool rotational axis via a guiding assembly, which can be rotated about the tool rotational axis in the spindle housing. In order to axially advance the tool holding portion, the guide assembly has a plurality of linear mounting elements, which are distributed about the tool rotational axis in a uniform manner, and respective paired guide rods, which are connected to the tool holding portion in a traction- and pressure-resistant manner.

The invention relates to a tool spindle for a device for fine machining optically active surfaces on workpieces, having a spindle housing and a tool holding portion which protrudes beyond the housing. The tool holding portion can be axially advanced towards the workpiece along a tool rotational axis via a guiding assembly, which can be rotated about the tool rotational axis in the spindle housing. In order to axially advance the tool holding portion, the guide assembly has a plurality of linear mounting elements, which are distributed about the tool rotational axis in a uniform manner, and respective paired guide rods, which are connected to the tool holding portion in a traction- and pressure-resistant manner.

A cutting apparatus includes: a processing feeding unit that performs processing feeding of a chuck table adapted to hold a workpiece; and two cutting units in which rotational axes of two spindles coincide with each other and cutting blades mounted to the spindles face each other. Each cutting unit includes a flange mechanism in which the cutting blade having a cutting edge fixed to an outer peripheral edge of a one-side outer surface of a circular disk-shaped base is fixed to the spindle. The flange mechanism is fixed to a tip of the spindle, sucks an other-side outer surface of the base of the cutting blade, and fixes the cutting blade to the spindle with the one-side outer surface of the base exposed to the side of the tip of the spindle, and the one-side outer surfaces of the cutting blades fixed to the two cutting units.

A glass-plate working apparatus 1 is comprised of a working head 7 for working an end face in a region R1 of an end face 6 of a glass plate 2; a moving means 10 for moving the working head 7 in an X direction along the end face in the region R1 of the glass plate 2; a working head 11 for working an end face in regions R2 and R3 of the end face 6 of the glass plate 2; and a moving means 12 for moving the working head 11 in the X direction along the end face in the regions R2 and R3 of the glass plate 2.

A glass-plate working apparatus 1 is comprised of a working head 7 for working an end face in a region R1 of an end face 6 of a glass plate 2; a moving means 10 for moving the working head 7 in an X direction along the end face in the region R1 of the glass plate 2; a working head 11 for working an end face in regions R2 and R3 of the end face 6 of the glass plate 2; and a moving means 12 for moving the working head 11 in the X direction along the end face in the regions R2 and R3 of the glass plate 2.

Provided is a method of manufacturing a glass sheet (G) having a disc shape including a cutout portion (Gb) in a peripheral edge portion (Ga), the method including etching the cutout portion (Gb).

A cutting apparatus includes: a processing feeding unit that performs processing feeding of a chuck table adapted to hold a workpiece; and two cutting units in which rotational axes of two spindles coincide with each other and cutting blades mounted to the spindles face each other. Each cutting unit includes a flange mechanism in which the cutting blade having a cutting edge fixed to an outer peripheral edge of a one-side outer surface of a circular disk-shaped base is fixed to the spindle. The flange mechanism is fixed to a tip of the spindle, sucks an other-side outer surface of the base of the cutting blade, and fixes the cutting blade to the spindle with the one-side outer surface of the base exposed to the side of the tip of the spindle, and the one-side outer surfaces of the cutting blades fixed to the two cutting units.

Provided is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording/reproducing apparatus, in which the total content of Li.sub.2O, Na.sub.2O, K.sub.2O, B.sub.2O.sub.3, and ZnO (Li.sub.2O+Na.sub.2O+K.sub.2O+B.sub.2O.sub.3+ZnO) is in a range of 0 mol % or more and 3 mol % or less, the mole ratio of the total content of Al.sub.2O.sub.3 and MgO relative to the total content of SiO.sub.2 and CaO [(Al.sub.2O.sub.3+MgO)/(SiO.sub.2+CaO)] is in a range of 0.30 or more and 0.6 or less, the total content of SiO.sub.2 and Al.sub.2O.sub.3 (SiO.sub.2+Al.sub.2O.sub.3) is in a range of 64 mol % or more and 85 mol % or less, and the total content of SiO.sub.2, Al.sub.2O.sub.3, MgO, and CaO (SiO.sub.2+Al.sub.2O.sub.3+MgO+CaO) is in a range of 87 mol % or more and 98 mol % or less.

The invention relates to a tool spindle for a device for fine machining optically active surfaces on workpieces, having a spindle housing and a tool holding portion which protrudes beyond the housing. The tool holding portion can be axially advanced towards the workpiece along a tool rotational axis via a guiding assembly, which can be rotated about the tool rotational axis in the spindle housing. In order to axially advance the tool holding portion, the guide assembly has a plurality of linear mounting elements, which are distributed about the tool rotational axis in a uniform manner, and respective paired guide rods, which are connected to the tool holding portion in a traction- and pressure-resistant manner.

The invention relates to a tool spindle for a device for fine machining optically active surfaces on workpieces, having a spindle housing and a tool holding portion which protrudes beyond the housing. The tool holding portion can be axially advanced towards the workpiece along a tool rotational axis via a guiding assembly, which can be rotated about the tool rotational axis in the spindle housing. In order to axially advance the tool holding portion, the guide assembly has a plurality of linear mounting elements, which are distributed about the tool rotational axis in a uniform manner, and respective paired guide rods, which are connected to the tool holding portion in a traction- and pressure-resistant manner.